1. One of the most productive composers who created popular music, Schubert writes down the beautiful thoughts in which include different notes. -> which (주격관계대명사)

2. A deadly disease has seriously influenced on many countries, but Korea, which is closely located to them, has been remained free of the disease. -> remained (수동태 불가)

3. One's memories grow far sharper despite a long passage of time has gone, but they can be reorganized by many events in which old ones are replaced by new ones. -> though (접속사 필요)

4. While awaiting the birth of a new baby, a parent typically furnishing a room with adorable materials have encouraged the nighttime separation. -> has been encouraged (or has encouraged?)

(수일치, 수동태?)

5. Hardly are halfhearted individuals distinguish for courage even when it includes their own welfare. -> 모름ㅠㅠ Hardly~distinguish 이 사이에 답이 있을 것 같은데ㅠㅠ